中文摘要：

【目的】为阐明长期施肥对红壤和潮土不同大小颗粒有机碳含量和分布的影响,探讨土壤持续利用培肥模式。【方法】采集17年长期施用不同肥料后的红壤和潮土,通过物理分组方法得到砂粒、粗粉粒、细粉粒、粗黏粒及细黏粒,观测了不同颗粒有机碳含量和分布的状况。【结果】与不施肥（CK）相比,施用有机肥（M、NPKM）和秸秆还田（NPKS）均可显著增加红壤和潮土总有机碳及不同颗粒有机碳组分的含量,其中以配施有机肥效果最为明显。施化肥有利于增加细黏粒的有机碳含量。各级颗粒中以砂粒的有机碳（POC）含量增幅最高,在红壤和潮土中分别增加1.7～3.8倍和1.9～2.8倍,对施肥最敏感。施肥使红壤和潮土有机碳在砂粒中的分布比例分别提高了37.7%～91.5%和63.6%;黏粉粒中有机碳的分布比例因颗粒大小不同而有差异,但总体上施肥降低了黏粉粒中矿物结合态有机碳（MOC）的分布比例,相应地施肥提高了POC与MOC的比率（WPOC/WMOC）,改良了土壤有机碳性质。【结论】长期施肥下壤质红壤比轻质潮土固存了更多的有机碳。配施有机肥和秸秆还田是提高两种土壤不同颗粒有机碳含量的有效措施。

英文摘要：

[Objective] The objective of this study was to clarify the effect of long-term fertilization on content and distribution of organic carbon in particle-size fractions in red soil and fluvo-aquic soil, and discuss fertility maintaining model for sustainable land use. [Method] The red soil and fluvo-aquic soil with different long-term fertilizations, collected from the seventeen years filed experiments, were separated into sand, coarse silt, fine silt, coarse clay and fine clay by physical way, and the content and distribution of organic carbon in these particle-size fractions were analyzed. [Result] Compared with treatment of CK, the treatment of M, NPKM and NPKS significantly increased the content of total organic carbon （TOC） and organic carbon in particle-size fractions in the two soils, however, application of chemical fertilizer was more favorable for increasing organic carbon in fine clay, Application of manure was the most effective practice for increase soil organic carbon. The POC in sand was the most sensitive fraction to the fertilization among the particle-size organic carbon fractions, as its increase extent of the content was the highest after fertilization and reached 1.7-3.8 times and 1.9-2.8 times in the red soil and fluvo-aquic soil, respectively. The distribution percentage of organic carbon in sand was significantly increased after fertilization by 37.7%-91,5% and 63.6% in the red soil and fiuvo-aquic soil, respectively. However, the percentage in different-sized clay and silt was significantly different, but it was decreased as a whole, followed by corresponding increase the ratio of POC to MOC （Wpoc/WMoc）, which aroused improvement of soil organic carbon. [ Conclusion] Loam red soil could retain more organic carbon than light fluvo-aquic soil and the application of organic manure or straw is a better way to increase organic carbon in particle-size fractions of the two soils.